Assembled monolayer of silicalite-1 (AMS) microcrystals on Si wafer for carbon nanotube (CNT) gro... more Assembled monolayer of silicalite-1 (AMS) microcrystals on Si wafer for carbon nanotube (CNT) growth has been prepared by the rubbing method. Iron oxide (α-Fe2O3, hematite) catalyst films were deposited onto silicate-1 monolayers from a Fe2O3 target by radio frequency (rf)-sputtering. This approach has the potential for producing well-aligned CNTs with controlled diameter from predesigned silicalite-1 templates by catalytic chemical vapor deposition (CCVD). Silicalite-1 monolayer oriented with faces parallel to Si wafer showed only the planes in the forms {0 k 0} lines at (020), (040), (060), (080) and (0100) by XRD. The formation and growth of CNTs by CCVD were achieved on the pores of silicate-1 crystals whereby the pores can be defined as confined spaces (channels, 5.60 Å) in nanometer dimensions acting as a template for a fine dispersion of well-defined Fe2O3 (10-15 nm) particles.
Wet foams formed through direct foaming were stabilized using various concentrations of amphiphil... more Wet foams formed through direct foaming were stabilized using various concentrations of amphiphilic particles that could control pore size and porosity. Microstructures and wet foam stability were tailored by amphiphile concentration, particle concentration, contact angle and pH of the suspension to obtain crack-free porous solid after sintering. The influence of these parameters on the porosity was satisfactorily described in terms of combined effects of the contact angle and particle concentration of the initial suspensions, directly affected by amphiphile concentration. Pores were obtained with sizes of c. a 30 - 300 µm and porosities of over 80%.
Wet foams formed through direct foaming were stabilized using various concentrations of amiphiphi... more Wet foams formed through direct foaming were stabilized using various concentrations of amiphiphilic particles that could control pore size and porosity. These porous materials showed moderate strength upon compression with high porosity. Bubble size and wet foam stability were tailored by amphiphile concentration, particle concentration, contact angle, and pH of the suspension to obtain crack-free porous solid after sintering. Closed and open pores were obtained with sizes of 30~300 µm and porosities of over 80%.
Macro porous ceramics possessing controlled microstructures and chemical compositions have increa... more Macro porous ceramics possessing controlled microstructures and chemical compositions have increasingly proven useful in the industrial sphere. Their sintered structures have found application in both established and emerging, areas such as thermal insu-lation in buildings, filtration of liquids and molten materials, refractory insulation, bone scaffolds and tissue engineering. Stable ceramic foams can be formed by wet chemical methods using inorganic particles(e.g., Al 2 O
This study presents a novel method to produce self-setting inorganic foams with a unique setting ... more This study presents a novel method to produce self-setting inorganic foams with a unique setting time and pore structure. The combination of the particlestabilized foams with Portland cement (Ca3SiO5) reaction leads to a macro porous ceramic material which can be shaped and consolidated at room temperature. The foam microstructure and porosity can be tailored varying different parameters such as setting temperature, humidity, cement and setting accelerator concentration. The final microstructure featured a porosity of nearly 65% and a unique pore structure with prevailing hydration reaction of cement. As a result, self-setting ceramic composites with porosities ranging from 40 to 65% and pores with sizes between 100 μm to 1 mm were achieved. Compared with other methods, this process used to produce self-setting inorganic macro porous materials is simple and cost effective, and opens a door for applications where until now drying and sintering phases were the limiting factors.
Assembled monolayer of silicalite-1 (AMS) microcrystals on Si wafer for carbon nanotube (CNT) gro... more Assembled monolayer of silicalite-1 (AMS) microcrystals on Si wafer for carbon nanotube (CNT) growth has been prepared by the rubbing method. Iron oxide (α-Fe2O3, hematite) catalyst films were deposited onto silicate-1 monolayers from a Fe2O3 target by radio frequency (rf)-sputtering. This approach has the potential for producing well-aligned CNTs with controlled diameter from predesigned silicalite-1 templates by catalytic chemical vapor deposition (CCVD). Silicalite-1 monolayer oriented with faces parallel to Si wafer showed only the planes in the forms {0 k 0} lines at (020), (040), (060), (080) and (0100) by XRD. The formation and growth of CNTs by CCVD were achieved on the pores of silicate-1 crystals whereby the pores can be defined as confined spaces (channels, 5.60 Å) in nanometer dimensions acting as a template for a fine dispersion of well-defined Fe2O3 (10-15 nm) particles.
Wet foams formed through direct foaming were stabilized using various concentrations of amphiphil... more Wet foams formed through direct foaming were stabilized using various concentrations of amphiphilic particles that could control pore size and porosity. Microstructures and wet foam stability were tailored by amphiphile concentration, particle concentration, contact angle and pH of the suspension to obtain crack-free porous solid after sintering. The influence of these parameters on the porosity was satisfactorily described in terms of combined effects of the contact angle and particle concentration of the initial suspensions, directly affected by amphiphile concentration. Pores were obtained with sizes of c. a 30 - 300 µm and porosities of over 80%.
Wet foams formed through direct foaming were stabilized using various concentrations of amiphiphi... more Wet foams formed through direct foaming were stabilized using various concentrations of amiphiphilic particles that could control pore size and porosity. These porous materials showed moderate strength upon compression with high porosity. Bubble size and wet foam stability were tailored by amphiphile concentration, particle concentration, contact angle, and pH of the suspension to obtain crack-free porous solid after sintering. Closed and open pores were obtained with sizes of 30~300 µm and porosities of over 80%.
Macro porous ceramics possessing controlled microstructures and chemical compositions have increa... more Macro porous ceramics possessing controlled microstructures and chemical compositions have increasingly proven useful in the industrial sphere. Their sintered structures have found application in both established and emerging, areas such as thermal insu-lation in buildings, filtration of liquids and molten materials, refractory insulation, bone scaffolds and tissue engineering. Stable ceramic foams can be formed by wet chemical methods using inorganic particles(e.g., Al 2 O
This study presents a novel method to produce self-setting inorganic foams with a unique setting ... more This study presents a novel method to produce self-setting inorganic foams with a unique setting time and pore structure. The combination of the particlestabilized foams with Portland cement (Ca3SiO5) reaction leads to a macro porous ceramic material which can be shaped and consolidated at room temperature. The foam microstructure and porosity can be tailored varying different parameters such as setting temperature, humidity, cement and setting accelerator concentration. The final microstructure featured a porosity of nearly 65% and a unique pore structure with prevailing hydration reaction of cement. As a result, self-setting ceramic composites with porosities ranging from 40 to 65% and pores with sizes between 100 μm to 1 mm were achieved. Compared with other methods, this process used to produce self-setting inorganic macro porous materials is simple and cost effective, and opens a door for applications where until now drying and sintering phases were the limiting factors.
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Papers by Ashish Pokhrel